Sen. Loudon is a self-employed insurance broker. He is a member of the Ballwin Baptist Church; West County Chamber of Commerce; Chesterfield Chamber of Commerce; the Young Republicans; Pachyderms; and Delta Tau Delta International Fraternity.

A 1985 graduate of Parkway West High School, Sen. Loudon received a bachelor of science degree from Westminster College in 1989 and is working toward a masters degree in public administration from the University of Missouri-Columbia.

Sen. Loudon was named Taxpayer Watchdog of the Year for 1995 (his first year in the Capitol) and was named Legislator of the Year in 1996 by the Alliance for Animal Legislation. In 1998, Sen. Loudon was named chairman of ALEC's subcommittee on State Tax Limitation.

Born August 14, 1967, Sen. Loudon resides in Ballwin, with his wife Dr. Gina Gentry Loudon and children, Lyda Lindsey, Elizabeth Love and John William, Jr. (Jack).